There's no such thing as a "defensive patent." No matter how good the intentions of the companies amassing these patents, as the recent Yahoo! broadside against Facebook shows, desperate times make for desperate patent-holders. And a desperate patent-holder will struggle against the temptation to become a troll.
Just ask Andy …

Great Convention

A practicable solution would be for firms to group themselves in a consortium that pledges to retaliate against any firm using patents against a member. Sort of like the Great Convention in Dune: "Use of atomics against humans shall be cause for planetary obliteration."

Some things can't be fixed, or, if they can, they should not be. Patents and Copyrights are two such things. I can see a 7 year exclusive commercial use patent and copyright, for physical devices and for creative works, as to their commercial sale or rental. I cannot see any use for software patents. Yes to Copyright as to the sale of software commercially.

Further I cannot see any reason why a private individual should be subject to any sort of patent, copyright, or license if he has first purchased an item be it hardware, software, or some (other) sort of creative work. Nor can I see any of those (patent, copyright, license) having application to any private individual in the non-commercial offering including duplication and transfer of such hardware or software or work to another private individual.

I think that the Constitution clearly gives Congress authority to establish patents and copyright and presumably by extension laws providing for licensing as well. But the constitution also guarantees free speech.

Congress, the Court, or the armed population should alter the patent, copyright, and licensing regime as I suggest on grounds of free speech, with NO compensation to the alleged "owners" of these plainly unconstitutional patents, copyrights, and licenses.